Unfortunately, I think all traces of that Jason Chan video have pretty much vanished, but there is a set of brushes you can download that have a brush that works very similarly to the general way the grainy circle brush did.

If you go to that site and go partway down the page (to the "Corel Painter-related goodies" area), you'll see a brush set called "Rob's custom Painter brushes". Download those and install them -- "Rob's Bristle Round" and "Rob's Basic" tend to work along the same lines. I actually use them now, in lieu of the original grainy circle brush I have on this list. (They're even on my updated list of brushes I use here: [link] )